Summary: The goal of this proposal is to develop and validate a cost effective, easy-to-use and fully integrated navigation system for needle placement during CT image-guided cancer diagnosis and treatment. Background: Accurate diagnostic and therapeutic interventions depend on accurate needle insertion, which is subject to the physician's visuospatial ability and experience, and could be difficult in certain tumor locations. Many publications agree that needle navigation systems could improve the targeting accuracy of CT image- guided needle insertions compared to the standard manual procedure. However, many navigation systems on the market are too expensive, and some require standard needles to be modified, increasing costs further. Additionally, some greatly affect the procedural workflow and are not likely to be widely adopted in clinical practice. Therefore, we propose a cost-effective, accurate, and easy-to-use needle navigation system. Significance: 600,000 people died from cancer and 1.6 million new cases of cancer were diagnosed in the U.S. in 2016. U.S. cancer care expenditures are expected to grow from $125 billion in 2010 to $156 billion in 2020. Hypotheses: Our system will enable image-guided cancer diagnosis/treatment planning and procedure execution in a streamlined workflow with increased accuracy, shortened procedure time, and reduced cost. Innovation: We will combine treatment planning, needle tracking, insertion navigation, and targeting verification in one fully integrated system that is designed for use with CT-guided percutaneous procedures. Methodology: In preliminary work, we developed a compact needle clip tracker in collaboration with NIH and the University of Georgia. We then founded 3T Technologies LLC, which will further develop the design as well as license and commercialize the needle navigation system. Specific Aim 1: Develop software for treatment planning and needle navigation, and evaluate the system using a human abdominal phantom model. Milestone: Achieve targeting accuracy of <2.5 mm. Specific Aim 2: Integrate the needle clip tracker with the software and evaluate the efficacy of the system with swine validation studies. Milestone: Evaluate targeting accuracy and clinical workflow. Team: Our team is equipped with software and hardware expertise and excellent imaging infrastructure. Expected Outcome/Impact: Our system will provide a simplified clinical workflow for effective and accurate CT-guided needle placement, which will reduce problems associated with needle targeting errors such as misdiagnosis, ineffective treatment, injury of critical anatomy, and other side effects. The relevance of this research to public health is the improvement of diagnostic and treatment outcomes, patient quality of life post-treatment, and the reduction of health care costs.